Some fuel cells are powered by hydrogen. scientists are looking into the decomposition of water (h2o) to make hydrogen fuel with the of the sun’s energy. what challenge do scientists face with this task?

Which statement correctly describes metallic bonds? a. they form when certain atoms lose electrons and other atoms gain electrons. b. they involve an attraction between anions and cations. they always involvpoth a metal and a nonmetal. d. they can only form between atoms of the same element. e. they form because electrons can move freely between atoms.

Ageochemist examines a piece of metal that he found in the soil. he performs tests to identify the metal from its density, electrical conductivity, and melting point. which statement best describes his investigation? a. he is determining physical properties that are sufficient to identify the metal. b. he is determining chemical properties that are sufficient to identify the metal. c. he is determining physical properties that are insufficient to identify the metal. d. he is determining chemical properties that are insufficient to identify the metal.

How many atoms or molecules are there in a mole of a substance?